Inspectors believe the blaze began when a band’s small pyrotechnics show ignited foam sound insulating material on the ceiling, releasing a putrid haze that caused scores of university students to choke to death. Most victims died from smoke inhalation rather than burns in what appeared to be the world’s deadliest nightclub fire in more than a decade.

Survivors and the police inspector Marcelo Arigony said security guards briefly tried to block people from exiting the club. Brazilian bars routinely make patrons pay their entire tab at the end of the night before they are allowed to leave.

Patrons inside the club died from the toxic fumes and suffocated while others were trampled to death in the stampede to get out. Reportedly one of the exits was locked, leaving only one door which quickly became jam packed. Firefighters who responded initially were unable to enter the club because of bodies blocking the entrance.

The pyrotechnics, or a flare, set off by a member of the band called Gurizada Fandangueira, lit the soundproofing materials in the venue’s ceiling, which spread rapidly and spelled doom for those who couldn’t make it outside.

“Large amounts of toxic smoke quickly filled the room, and I would say that at least 90 percent of the victims died of asphyxiation,” Beltrame told the AP. “The toxic smoke made people lose their sense of direction so they were unable to find their way to the exit. At least 50 bodies were found inside a bathroom. Apparently they confused the bathroom door with the exit door.”

Funerals for the victims have already started. According to reports, many of the victims were less than 20 years-old.

See photos of the grim and chaotic scene and it’s aftermath in the gallery.

Our prayers and condolences go out to the families and friends of all the victims.